Islamic State (IS) militants killed 37 rival rebels during overnight battles in Syria's northern province of Aleppo, Xinhua reported.
Another 20 rebels have gone missing during the violent attack IS waged against the town of Um Housh in the northern countryside of Aleppo Friday, according to the Syrian Observatory for Human Rights.
IS initiated the attack through a suicide car bombing targeting the rebels' town posts, said the Observatory, adding that US-led anti-terror warplanes are believed to have struck IS in that area.
IS lost 10 militants in the attack, but gained control of the entire town, a victory deemed crucial for IS militants in their advance to secure positions in the northern countryside of Aleppo.
The UK-based watchdog group said IS aims to advance towards the northern province of Aleppo to sever its northern countryside from the city of Aleppo.